The FABLE Calculator is an Excel accounting tool used to study the potential evolution of food and land-use systems over the period 2000-2050. The impact of different policies as well as changes in the drivers of these systems can be tested through the combination of a large number of scenarios. The FABLE Calculator focuses on agriculture as the main driver of land-use change. It includes 76 agricultural raw and processed products from the crop and livestock sectors (Appendix 1) and relies extensively on the FAOSTAT database for input data. In each 5-year time step over 2000-2050, the level of agricultural activities, land use, food consumption, trade, and greenhouse gas (GHG) emissions is computed according to selected scenarios. The current version of the FABLE Calculator is a light Excel file (<6 MB) which contains country or regional historical data in the grey “DATA” sheets, the formulas for the calculation in the green “CALCULATION” sheets, the scenarios definition and selection in the light red “SCENARIOS” sheets, and the visualization of the main results in the yellow “INDICATORS” sheets (Figure 1). Users can replace data from global databases with national or sub-national data. This is not an optimization tool and prices are only used ex-post to compute production and trade value (i.e. they do not influence the results and results do not influence commodity prices, contrary to economic models).
We developed the FABLE Calculator because we are convinced models can help frame better policies. First, models describe and explain in a simplified framework how things work. By integrating various sources of existing information, they highlight information gaps and inconsistencies as well as the different parts of a system that are connected. Second, models explore the potential impact of policies that are not in place, or changes that cannot be currently observed. Specifically, scenarios make it possible to test for the consequences of a wide range of "if" assumptions and their most important dependencies. The FABLE Calculator can identify major imbalances in, and threats to, national food and land-use systems without complex optimization algorithms. It can be opened on almost any computer since Excel is one of the most widely used programs in the world and newer versions are backwards-compatible with older Excel files. Because all of the data is visible and the structure of the functions is clear, the Calculator contains no hidden “black-box” that can obfuscate its weaknesses. Users can quickly select alternative combinations of scenarios and see the impacts on the main indicators. This is an advantage when interacting with stakeholders, as assumptions can be changed easily and transparently. In certain contexts, there may be some value in starting with a simple tool and progressively including more complexity to address clear shortcomings identified by stakeholders, rather than presenting a very complex tool whose value may not be well understood. However, results should be always challenged knowing the limitations of the tool, and some questions simply cannot be answered by the FABLE Calculator because it lacks the necessary complexity (cf. section 4.4 Discussion of the results in FABLE, 2019).
The Food, Agriculture, Biodiversity, Land-Use, and Energy (FABLE) Consortium is a collaborative initiative, operating as part of the Food and Land-Use Coalition, working to understand how countries can transition towards sustainable land-use and food systems. The Consortium is a global network of researchers organized by country teams who are building the tools and analyses for integrated food and land-use planning at the national and global level (Schmidt-Traub, Obersteiner, & Mosnier, 2019). Before joining the Consortium, few country teams had developed a model that covered both food and land systems. Therefore, the FABLE Calculator was developed with the objective of providing a model to each country team as quickly as possible to allow them to make first projections of their food and land-use systems up to 2050. Seventeen country models (Argentina, Australia, Brazil, Canada, China, Colombia, Ethiopia, Finland, Indonesia, India, Mexico, Malaysia, Russia, Rwanda, Sweden, the UK, and the USA) and seven rest-of-the world (RoW) regional models were produced to generate sustainable pathways. The FABLE Consortium played a key role in identifying problems and mistakes in the Calculator and in suggesting improvements.
The FABLE calculator has been used to play the first FABLE Scenathon, a process where the same standardized indicators derived from the modeled pathways of all country teams and rest of the world regions were submitted to an online platform (also called Linker tool) which allowed the comparison of the pathways, the aggregation at the global level, and the computation of trade imbalance for each product and year. Several iterations have been used to balance trade and to try to collaboratively align national pathways with the global FABLE targets. The results and methodology of this first Scenathon are described in the FABLE Report 2019 (FABLE, 2019).
More generally, the FABLE Calculator can be used by anyone who is interested in integrated analyses of food and land-use systems. It is especially suitable for people with no or limited previous experience in modelling.